Abstract
Parallel-Tube Heat Transport Device (PT-HTD) shows high heat-transport efficiency because of spontaneous internal flow converting both sensible and latent heats. PT-HTD consists of multiple tubes and two headers in which working fluid vaporizes and condenses. In our previous study, the effects of tube diameter, tube number, operating orientation, working fluid, and volumetric filling ratio on heat transport rate were clarified. However, internal flow patterns or flow mode has not been quantitatively evaluated yet. In this study, the experiments for two different diameters (2.4 and 4.4mm) and three different working fluids (water, ethanol and FC-72) were performed. Internal flow patterns were captured by using a high-speed camera, and its temporal and spatial change was identified by using image analysis. The results showed variation of internal flow patterns depending on tube inner diameter, working fluid and heat transport rate. Furthermore, long-interval flow-pattern changing was observed for high heat transport range.
